We examined the role of trees as grooming objects in grazing pasture and investigated their necessity. Four grazing Japanese Black cows were used. Experimental pastures with restricted (RST) and released (RLS) grooming with trees were established. Examination was carried out for 24 h in each RST and RLS. The respective frequencies and duration of self-grooming, allo-grooming (social grooming) and grooming with trees was recorded by a continuous scan sampling method, and maintenance behavior was recorded by a 2-min group animal scan sampling method. Grooming with trees in RLS occurred 29 12 times/24 h and for 1342 475 s/24 h. Total frequencies and duration of grooming in RLS tended to increase from that in RST (P = 0.08, P = 0.06, respectively). However, self-grooming and allo-grooming exhibited no differences. The results indicate that cattle may enrich their grooming through the use of trees if the latter are available. Furthermore, they may not substitute grooming with trees with other forms of grooming if no trees are available in the grassland. No difference was observed in the general proportion of their maintenance behavior. These results suggest that trees in grassland provide a good environmental enrichment object that satisfies cattle’s potential needs of grooming and did not restrict their general behavior.